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Fifty-two magnetic white dwarfs have been identified in spectroscopic observations from the Sloan Digital Sky Survey (SDSS) obtained between mid-2002 and the end of 2004, including Data Releases 2 and 3. Though not as numerous nor as…

We performed kinematic studies of the evolution of small-scale magnetic fields in the surface laters of M-dwarfs. We solved the induction equation for a prescribed velocity field, magnetic Reynolds number, and boundary conditions in a…

Astrophysics · Physics 2009-11-07 S. B. F. Dorch , H. -G. Ludwig

In this work, we study the properties of magnetized white dwarfs taking into account possible instabilities due to electron capture and pycnonuclear fusion reactions in the cores of such objects. The structure of white dwarfs is obtained by…

Solar and Stellar Astrophysics · Physics 2017-03-31 Edson Otoniel , Bruno Franzon , Manuel Malheiro , Stefan Schramm , Fridolin Weber

Evidence of surface magnetism is now observed on an increasing number of cool stars. The detailed manner by which dynamo-generated magnetic fields giving rise to starspots traverse the convection zone still remains unclear. Some insight…

Solar and Stellar Astrophysics · Physics 2017-09-20 Maria A. Weber , Matthew K. Browning , Suzannah Boardman , Joshua Clarke , Samuel Pugsley , Edward Townsend

We consider a model where the strong magnetic fields of magnetars arise from a high baryon density, magnetized core. In this framework magnetars are distinguished from pulsars by their higher masses and central density. For magnetars, as…

Solar and Stellar Astrophysics · Physics 2015-05-20 N. D. Hari Dass , Vikram Soni

Cool stars like the Sun harbor convection zones capable of producing substantial surface magnetic fields leading to stellar magnetic activity. The influence of stellar parameters like rotation, radius, and age on cool-star magnetism, and…

Solar and Stellar Astrophysics · Physics 2015-06-04 Ansgar Reiners

Magnetic fields with strengths ranging from 300 to 500 kG have recently been discovered in a group of four extremely similar helium-enriched hot subdwarf (He-sdO) stars. Besides their strong magnetic fields, these He-sdO stars are…

Solar and Stellar Astrophysics · Physics 2024-11-13 M. Dorsch , C. S. Jeffery , A. Philip Monai , C. A. Tout , E. J. Snowdon , I. Monageng , L. J. A. Scott , B. Miszalski , V. M. Woolf

Magnetic fields permeate the Universe on all scales and play a key role during star formation. We study the evolution of magnetic fields around a massive metal-free (Population III) star at $z \sim 15$ during the growth of its HII region…

Astrophysics of Galaxies · Physics 2016-08-03 Daegene Koh , John H. Wise

Magnetic fields play a vital role in numerous astrophysical processes such as star formation and the interstellar medium. In particular, their role in the formation and evolution of galaxies is not well understood. This paper presents…

Astrophysics of Galaxies · Physics 2021-12-10 Huai-Hsuan Chiu , Ke-Jung Chen

M dwarfs are the most abundant stars in the Galaxy and exhibit diverse magnetic behaviours. Understanding their large-scale magnetic fields is essential to study stellar dynamos and assess the impact of magnetic activity on planetary…

The chemical evolution of nascent quark matter core in a newborn compact neutron star is studied in presence of a strong magnetic field. The effective rate of strange quark production in degenerate quark matter core in presence of strong…

Astrophysics · Physics 2009-10-31 Tanusri Ghosh , Somenath Chakrabarty

We have detected longitudinal magnetic fields between 2 and 4kG in three normal DA white dwarfs (WD0446-790, WD1105-048, WD2359$-$434) out of a sample of 12 by using optical spectropolarimetry done with the VLT Antu 8 m telescope equipped…

Astrophysics · Physics 2007-05-23 R. Aznar Cuadrado , S. Jordan , R. Napiwotzki , H. M. Schmid , S. K. Solanki , G. Mathys

Some main-sequence stars of spectral type A are observed to have a strong (300-30000 G), static, large-scale magnetic field, of a chiefly dipolar shape -- the `Ap stars' (for example Alioth, the fifth star in the Big Dipper). Following…

Astrophysics · Physics 2009-11-10 J. Braithwaite , H. C. Spruit

Electron captures by atomic nuclei in dense matter are among the most important processes governing the late evolution of stars, limiting in particular the stability of white dwarfs. Despite considerable progress in the determination of the…

Solar and Stellar Astrophysics · Physics 2023-04-05 N. Chamel , L. Perot , A. F. Fantina , D. Chatterjee , S. Ghosh , J. Novak , M. Oertel

Enormous progress has been made on observing stellar magnetism in stars from the main sequence through to compact objects. Recent data have thrown into sharper relief the vexed question of the origin of stellar magnetic fields, which…

Solar and Stellar Astrophysics · Physics 2015-06-24 Lilia Ferrario , Andrew Melatos , Jonathan Zrake

There is solid observational evidence on the existence of massive, $M\sim 1~M_\odot$, highly magnetized white dwarfs (WDs) with surface magnetic fields up to $B\sim 10^9$ G. We show that, if in addition to these features, the star is fast…

High Energy Astrophysical Phenomena · Physics 2017-01-11 D. L. Caceres , S. M. de Carvalho , J. G. Coelho , R. C. R. de Lima , Jorge A. Rueda

We investigate the luminosity suppression and its effect on the mass-radius relation as well as cooling evolution of highly magnetised white dwarfs. Based on the effect of magnetic field relative to gravitational energy, we suitably modify…

Solar and Stellar Astrophysics · Physics 2022-04-06 Mukul Bhattacharya , Alexander J. Hackett , Abhay Gupta , Christopher A. Tout , Banibrata Mukhopadhyay

A deep imaging survey covering the entire $23\arcmin$ diameter of the old open cluster M67 to $V = 25$ has been carried out using the mosaic imager (UHCam) on the Canada-France-Hawaii Telescope. The cluster color-magnitude diagram (CMD) can…

Astrophysics · Physics 2009-10-30 Harvey B. Richer , Gregory G. Fahlman , Joanne Rosvick , Rodrigo Ibata

Ultra-massive white dwarfs are powerful tools to study various physical processes in the Asymptotic Giant Branch (AGB), type Ia supernova explosions and the theory of crystallization through white dwarf asteroseismology. Despite the…

Many stars across all classes possess strong enough magnetic fields to influence dynamical flow of material off the stellar surface. For the case of massive stars (O and B types), about 10\% of them harbour strong, globally ordered (mostly…

Solar and Stellar Astrophysics · Physics 2023-04-05 Asif ud-Doula , Stan Owocki